The modern marine terminal must efficiently process an increasing number of containers in an area of limited space with little, if any, land available for expansion. Capacity demands are increasing rapidly with higher volumes of container traffic worldwide and new, larger container ships coming on-line. Specific containers should be located on demand among the thousands of containers at any given time, but this can be difficult if there is a lack of an accurate and real-time container identification and tracking system of drayage tractors, switched tractors, wheeled container chassis, top and side pick loaders, and gantry and quay cranes. Locating a container can also be complicated by the number of ways in which containers can be processed through a terminal. For example, some containers arrive via a vessel or train and are driven through a check-in gate by an outside truck. Once a container enters the terminal, it can be parked on a chassis or bombcart in a terminal, or removed from the chassis and placed on top a stack of shipping containers. When a container is to be retrieved, it must be located among the thousands of containers in the terminal. These containers may be moved around the terminal by outside drivers, or moved by marine terminal drivers, using a client's tractor with terminal equipment.
Maintaining inventory and track of every container in the terminal is difficult and the large number of containers and the different ways in which the containers can be moved throughout the terminal makes it difficult to locate a specific container when it is needed. Also, the marine terminal often does not run smoothly and this complicates the location system.
Different systems are used for processing containers through a marine terminal, such as discharging a container from a vessel to chassis. For example, containers may arrive in a marine terminal via a vessel or rail. Other containers can be discharged from a vessel to ground. When containers arrive at a marine terminal via a vessel or train, they can be “discharged” or placed on a bombcart/port trailer to be stacked, instead of parked on a chassis. Other containers can be checked in at a gate. Instead of arriving via a vessel or train, a container may arrive via a central check-in gate. Drivers employed by customers of the marine terminal arrive at the gate for check-in, where they pass through a gate much like a highway toll plaza. At this gate, information is collected about the container, after which the driver is instructed either to park the chassis and container in a particular location or to discharge the container to ground.
These different systems for processing containers make it difficult to track the containers in a marine terminal. Tracking container movement throughout the marine terminal is important because searching for any misplaced containers requires time and labor costs and adds to the shipping time of goods.
One prior art system uses brightly colored, highly distinctive sticker magnets placed on each container. Terminal employees walk around the terminal looking for these magnets and noting their locations when they are found. This solution is accurate, but the containers could be moved within the terminal after the sticker magnets have been sighted, and the process of searching for sticker magnets on containers is labor-intensive. There is also a time-lag in obtaining data using this method.
Other prior art systems use wireless technology to track the location of containers within a marine terminal. These systems require some human intervention to locate items, and may have some lag time for data collection. Although some of these described or other prior art systems may provide for tracking parked containers on a chassis (wheeled), it is even more difficult to track stacked containers (grounded).
A system for tracking cargo containers contained within a terminal such as a modern marine terminal that overcomes many of the drawbacks noted above is disclosed in commonly assigned U.S. Patent Publication No. 2006/0220851, filed Aug. 11, 2006 as U.S. patent application Ser. No. 11/201,956, the disclosure which is hereby incorporated by reference in its entirety. The system includes a tag transmitter adapted to be positioned on container handling equipment and operative for transmitting a wireless RF signal based on an event affecting the location of a container handled by the container handling equipment. A plurality of spaced apart access points are positioned at known locations within the terminal that receive the wireless RF signals from the tag transmitter. A processor is operatively connected to the locating access points for geolocating the tag transmitter and determining the container location at the time the event occurs.
In another aspect, a sensor is adapted to be mounted on the container handling equipment and operative with the tag transmitter for sensing an event and transmitting data to the tag transmitter for transmission of event data from the tag transmitter. The sensor is operative for sensing the removal, placement or release of a container, and the height of any gripper located on the container handling equipment to indicate the height of a container when stacked with other containers.
In some cases, it is necessary to verify the position of mobile equipment such as shuttle trucks (STs) and utility tractor rigs (UTRS) at specific points in the terminal. It is also desirable to provide some type of permanent milepost indication at the terminal as a crossing indication, or an X/Y location as a grid-of-tags.